【摘要】 体外单一药物诱导标准大肠杆菌ATCC25922,获得了耐氯霉素(CHL,MIC≥256 mg/L)、耐环丙沙星(CIP,MIC≥256 mg/L)、耐水杨酸钠(SAL,MIC≥275 mg/L)、耐四环素(T,MIC≥512 mg/L)的菌株。选取ATCC25922株,4株中度耐药菌SAL(175)、CHL(64)、T(64)、CIP(128),4株高度耐药菌SAL(275)、CHL(256)、T(512)、CIP(256),和临床分离的3株耐药大肠杆菌H1、H9、H10,通过实时荧光定量RT-PCR方法检测外输泵AcrA基因的mRNA表达水平。系统自动分析软件显示,Ct值与标准质粒浓度的对数之间存在良好的线性关系,回归系数为0.992。检测结果表明:H10、CHL(256)、CIP(256)拷贝数最高,达1015拷贝/μL;T(512)、H9、T(128)、SAL(275)、H1为1014拷贝/μL;CHL(128)、T(64)、CHL(64)为1013拷贝/μL;ATCC25922为1012拷贝/μL。不同程度耐药株AcrA基因的表达量不同,临床分离株和诱导的各高耐药菌株均比ATCC25922株表达量高,且差异极显著(P≤0.01)。这说明不同耐药程度的11株菌cDNA的量存在差异,AcrA基因转录水平与耐药水平成正相关。更多还原

【Abstract】 E.coli ATCC25922 strains were induced by in vitro sole medicine to obtain chloramphenicol-resistant strain(CHL,MIC≥256 mg/L),ciprofloxacin-resistant strain(CIP,MIC ≥256 mg/L),natrium salicylicum-resistant strain(SAL,MIC≥275 mg/L) and tetracycline-resistant strain(T,MIC≥512 mg/L).ATCC25922,four higher drug-resistant strains including SAL(275),CHL(256),T(512),CIP(256),four midrange drug-resistant strains including SAL(175),CHL(64),T(64),CIP(128) and three strains including H1,H9,H10 from ten clinical strains,the mRNA expression of AcrA gene of which were detected by real-time fluorescent quantitative PCR.The results showed there was a good linear function in statistics between the Ct value and the concentration gradient of standard plasmid DNA specimen with the regression value of 0.992.The highest copies/μL of H10,CHL(256) and CIP(256) were 1015;the copies/μL of T(512),H9,T(128),SAL (275) and H1 strains reached 1014;the copies/μL of CHL(128)、T(64)、CHL(64)reached 1013,ATCC25922 reached 1012.The copies of different strains mRNA expression quantity were distinct.Each higher drug-resistant strain from the clinical separation and induction must be higher than the ATCC2592 in expression quantity.It demonstrated that the expression quantity for 11 different levels of drug-resistant strains existed difference significantly(P<0.01) and that the gene transcription level revealed a positive correlation with the drug-resistant level.更多还原